1. Field of the Invention
The present invention relates to a process for producing a magnetic head that records information on a magnetic disk with a magnetic field, a magnetic head and a magnetic disk unit, and more particularly, it relates to a magnetic head attaining high speed and high density recording, a magnetic disk unit using the magnetic head and a process for producing a magnetic head that is excellent in reproducibility and is relatively inexpensive.
2. Description of the Related Art
The recording density of hard disk recording units (hard disk drive, commonly abbreviated as HDD) is increasing by 100% per year in recent years, and it is reaching 100 Gb/(inch)2 in an experimental phase. However, due to the superparamagnetic effect and the difficulty in reducing the gap width of the magnetic head, recording density of the conventional HDD is approaching its limitation. As a measure against the superparamagnetic effect, a perpendicular magnetic film or a multilayer structure using an antiferromagnetism film as an underlayer have been developed to obtain a perspective of a density of 300 Gb/(inch)2. Rather, a reduction of the width of the magnetic pole of the magnetic circuit has become a serious problem.
FIGS. 7A to 7E show a conventional typical magnetic head and a magnetic recording transducer used therefor. As shown in FIG. 7A, a magnetic head 1 has a magneto-resistive sensor 3 and a magnetic recording transducer 4 consecutively piled on a back end surface 2a of a flying slider 2, and the head 1 flies above a magnetic recording layer 8a of a magnetic disk 8 by a flying surface 2b having a concave part 2c. The head records information with a magnetic field 49 leaked from the magnetic recording transducer 4, and reproduces information with the magneto-resistive sensor 3.
As shown in FIGS. 7B to 7D, the magnetic recording transducer 4 is formed in the following manner. A lower yoke 41 formed with a soft magnetic film functioning as a magnetic shield film of the magneto-resistive sensor 3, a dielectric film 47 as an insulating film, a thin film magnetic coil 44, and an upper yoke 42 formed with a soft magnetic film and constituting a magnetic circuit by connecting at a back end of the lower yoke 41 through a connecting part 43 are consecutively piled, and a magnetic pole 46′ is formed by narrowing the tip end of the upper yoke 42 by etching, so as to form a magnetic gap 48 between the magnetic pole 46′ and a magnetic pole 45′ at a tip end of the lower yoke 41. Thereafter, the surrounding of the upper yoke 42 is filled with a dielectric film 47′. As a method for forming the magnetic pole 46′, there is another method as shown in FIG. 7E, i.e., after attaching a dielectric film 47″, a gap for the magnetic pole 46′ is formed therein, and the magnetic pole 46′ is embedded in the gap. By passing an electric current in the thin film magnetic coil 44 of the magnetic recording transducer 4 thus produced, information is recorded on the magnetic recording film 8a by a leakage magnetic filed 49 from the magnetic poles 45′ and 46′.
The length of the magnetic gap 48 between the two magnetic poles 45′ and 46′ is determined by the thickness of the dielectric film 47, and the width of the magnetic gap 48 is determined by the width of the magnetic pole 46′ because the magnetic pole 45′ of the lower yoke 41 functioning as a magnetic shield film has a large width. The width of the magnetic gap 48, i.e., the width W of the magnetic pole 46′, can be narrowed to 130 nm by etching, and thus the recording density of the magnetic disk can be increased to 100 Gb/(inch)2. Furthermore, even when the width W of the magnetic pole 46′ is decreased, magnetic saturation is prevented by increasing the thickness T of the magnetic pole 46′. In order to attain a recording density of 300 Gb/(inch)2, the width W of the magnetic pole 46′ should be decreased to 50 to 60 nm.
According to the conventional production process of a magnetic head, however, when the width W of the magnetic pole 46′ is decreased to 50 to 60 nm, the thickness T of the magnetic pole 46′ is further necessarily increased to prevent magnetic saturation around the magnetic pole 46′, but a thick magnetic film is difficult to be subjected to microfabrication and results in poor reproducibility. In the method shown in FIG. 7E, it is difficult to form a gap of 0.1 μm or less in a stable manner, and it is also difficult to embed a metal for the magnetic pole in the gap.